After an almost five-year journey to the solar system’s
largest planet, NASA's Juno spacecraft successfully entered Jupiter’s orbit during
a 35-minute engine burn. Confirmation
that the burn had completed was received on Earth at 8:53 pm. PDT (11:53 p.m.
EDT) Monday, July 4.

“Independence Day always is something to celebrate, but today we
can add to America’s birthday another reason to cheer – Juno is at Jupiter,”
said NASA Administrator Charlie Bolden. “And what is more American than a NASA
mission going boldly where no spacecraft has gone before? With Juno, we will investigate
the unknowns of Jupiter’s massive radiation belts to delve deep into not only
the planet’s interior, but into how Jupiter was born and how our entire solar
system evolved.”

Confirmation of a successful orbit insertion was received from
Juno tracking data monitored at the navigation facility at NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, California, as well as at the Lockheed
Martin Juno operations center in Denver. The telemetry and tracking data were
received by NASA's Deep Space Network antennas in Goldstone, California, and
Canberra, Australia.

“This is the one time I don’t mind being stuck in a windowless
room on the night of the Fourth of July,” said Scott Bolton, principal
investigator of Juno from Southwest Research Institute in San Antonio. “The
mission team did great. The spacecraft did great. We are looking great. It’s a
great day.”

Preplanned
events leading up to the orbital insertion engine burn included changing the
spacecraft’s attitude to point the main engine in the desired direction and
then increasing the spacecraft’s rotation rate from 2 to 5 revolutions per minute
(RPM) to help stabilize it.

The
burn of Juno’s 645-Newton Leros-1b main engine began on time at 8:18 p.m. PDT (11:18
p.m. EDT), decreasing the spacecraft’s velocity by
1,212 mph (542 meters per second) and allowing Juno to be captured in orbit
around Jupiter. Soon after the burn was completed, Juno turned so that the
sun’s rays could once again reach the 18,698 individual solar cells that give
Juno its energy.

“The spacecraft worked perfectly, which is always nice when
you’re driving a vehicle with 1.7 billion miles on the odometer,” said Rick
Nybakken, Juno project manager from JPL. “Jupiter orbit insertion was a big
step and the most challenging remaining in our mission plan, but there are
others that have to occur before we can give the science team members the
mission they are looking for.”

Over the next few months, Juno’s
mission and science teams will perform final testing on the spacecraft’s
subsystems, final calibration of science instruments and some science
collection.

“Our official science collection phase begins in October, but
we’ve figured out a way to collect data a lot earlier than that,” said Bolton.
“Which when you’re talking about the single biggest planetary body in the solar
system is a really good thing. There is a lot to see and do here.”

Juno's principal goal is to understand the origin
and evolution of Jupiter. With its suite of nine science instruments, Juno will
investigate the existence of a solid planetary core, map Jupiter's intense
magnetic field, measure the amount of water and ammonia in the deep atmosphere,
and observe the planet's auroras. The mission also will let us take a giant
step forward in our understanding of how giant planets form and the role these
titans played in putting together the rest of the solar system. As our primary
example of a giant planet, Jupiter also can provide critical knowledge for
understanding the planetary systems being discovered around other stars.

The Juno spacecraft launched on Aug. 5, 2011, from Cape
Canaveral Air Force Station in Florida. JPL manages the Juno mission for NASA.
Juno is part of NASA's New Frontiers Program, managed at NASA's Marshall Space
Flight Center in Huntsville, Alabama, for the agency’s Science Mission
Directorate. Lockheed Martin Space Systems in Denver built the spacecraft. The
California Institute of Technology in Pasadena manages JPL for NASA.

What the Juno mission will look like

The Juno mission will cost Nasa $1.1billion.

After an epic five year journey, where it slung-shot around the Earth
to gather speed and travelled for 2.8bn kilometres, it will now circle Jupiter for 20 months, before plunging to a crushing death in Jupiter’s harsh and dense atmosphere.

Any reports we get from Juno actually happened 48 minutes and 19
seconds earlier – that’s how long it takes light to get from Juno to
Earth. As a result, it gets sent directions ahead of time, and is flown
essentially on auto-pilot.

Despite Juno’s sensitive electronics being encased in a one-inch
thick solid titanium box to shield it from the intense radiation around
Jupiter, eventually it will succumb to the harsh environment. At that
time – currently estimated to be in about 20 months – it will be
commanded to dive into the atmosphere.

But in that time, it will use it’s nine instruments to learn everything it can about Jupiter’s interior and atmosphere.

It will map Jupiter’s gravity and magnetic fields and track how much
water is in the atmosphere. Its colour camera dubbed JunoCam will snap
close-ups of Jupiter’s swirling clouds, polar regions and shimmering
southern and northern lights.